Best Tomato Seed Starting Tips: How to Nip Problems in the Bud

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Updated 1.8.2024

Tomato Dirt has gathered the best tomato seed starting tips to help get your new seedlings off to an excellent beginning.

It’s great when you pop seeds into potting mix and poof! -- healthy seedlings push their way into the world, problem-free.

But alas, things don’t always go that way. Seed starting can be tricky. A little information from a friend can go a long way.

The most important thing to do is to be vigilant. Germination is an important time in seedling development. If you know what symptoms to look for you can nip problems in the bud. Here are the biggees to watch for and some seed starting tomato tips that explain what to do if you spot one of them.

Damping off

Look for this
Tomato seeds don’t germinate
Seedling thins at the soil line, flops over and dies

Why does it happen?
Fungi in soil rot the seedling to death. The highest number of damping off victims are seedlings started in non-sterile soil.
Stagnant air, contaminated soil, and dirty pots, tools, and handling are the biggest culprits of spreading damping off.

Tomato Seed Starting Tips to help
Start seeds in artificial, sterile starter mix rather than real soil to eliminate the guilty fungi
Make sure your starter mix contains sphagnum moss, which has antibiotic qualities. You may also consider sprinkling a very thin coat of sphagnum moss on soil when planting seeds.
Give sprouting seeds circulation. Let some air into clear plastic lids or bags on planted containers. Thin sprouted seedlings.

Read more about damping off.

Leggy plants

Look for this
Stems are stretched, thin, and sometimes limp

Why does it happen?
Poor lighting
Too much heat
Too much fertilizer

Tomato Seed Starting Tips to help
Re-pot seedling (learn how to re-pot tomato seedlings), burying elongated stem up to first set of leaves
Give your tomato plant better light and more circulation

Slow growth

Look for this
Baby tomato seedlings take F-O-R-E-V-E-R to germinate and grow

What causes it
The room is too cold or the seedlings don’t have enough food

Tomato Seed Starting Tips to help
Warm up the room
Get rid of drafts
Fertilize seedlings lightly

Seed rot

Look for this
No seedlings! Seeds rot before they germinate.

Why does it happen?
Over watering

Seed Starting Tips to help
Plant seeds in moist but not soggy water
Mist planted seeds but don’t over water

Stuck leaves

Look for this
First leaves get stuck to seed coating and can’t break free

Why does it happen?
Being born is hard work

Seed Starting Tips to help
Be patient. Seed starting takes time.
Lightly mist leaves to get them soft and pliable. But don’t pinch of the leaves or your seedling will die.

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